The present invention relates to an improved construction for an inflatable cushion useful in opposing or side relation to a vehicle occupant. The present invention would also be useful for other types of transportation vehicles as well as machinery.
Inflatable protective cushions used in passenger vehicles are a component of relatively complex systems. The main elements of the systems are: an impact sensing device, an ignition system, a solid propellant material, an attachment device, a system enclosure, and an inflatable protective cushion. Upon sensing an impact, the propellant is ignited causing an explosive release of gas filling the cushion to a deployed state which can absorb the impact of a moving body.
Traditional driver""s side cushions have been of a generally circular shape constructed from two circular pieces formed from material such as 315-840 denier nylon yarn. These circular pieces are seamed together around their periphery using traditional sewing techniques. Although this product has preformed in an acceptable manner, it has generally been recognized that the formation of a seam is a relatively time consuming process. In addition, the sewn seam serves as an area through which the inflation gases may escape. Examples of sewn driver""s side cushions are provided in U.S. Pat. No. 5,533,755 to Nelsen et al. (incorporated by reference).
Passenger side cushions have to this point have been generally of a rather complex geometry formed from either single piece or multi-piece fabric panels. Such cushions, however have nonetheless continued to use basic sewn seams as the means of attaching and/or enclosing the panel structures.
It has recently been recognized that a cushion which deploys and has the capacity to remain inflated for a period of several seconds may provide substantial benefits when a vehicle is involved in a prolonged crash event such as a roll over situation. One such cushion is illustrated and described in U.S. Pat. No. 5,788,270 to Haland et al. (incorporated by reference). In such prolonged crash events, the cushion must be capable of accepting and maintaining a pressure for several seconds. In some embodiments this pressure may be as high as 40 or 50 psi. Accordingly, any seam structures must not serve as a conduit through which an inflation media can pass.
Haland et al. attempts to minimize pressure degradation within the impact cushion by substituting traditional sewn seems with interwoven connections between two layers of fabric such as may be formed using a jacquard weaving system. Notwithstanding the use of such interweaving technology, cushions formed according to the teachings in Haland et al. nonetheless require the application of at least two relatively heavy layers of silicone coating material in order to prevent the premature deflation of the airbag structure. The need for such coating is particularly acute at the interwoven seams which serve as the conduit through which the majority of the gas tends to escape.
Thus, whether a structure uses traditional sewn seems or interwoven connections between layers of fabric these points of joiner can unduly influence the rate of gas leakage from the cushion. Although other connective means, such as adhesives have been proposed, the strength of such seams has been generally unacceptable under heat aging conditions.
In view of the forgoing, it is a general object of the present invention to provide an inflatable restraint cushion possessing substantially leek proof seams and an increased inflation strength.
It is a further object of the present invention to provide an inflatable restraint cushion possessing leek proof seams in the form of a weld having a bond strength in both the peel and shear mode of not less that 10 lbs./inch, a fabric tensile strength of not less than 100 lbs./inch and, when inflated, a specific inflation strength less than 1.2.
It is an object of the present invention to provide an inflatable restraint cushion formed from welded material panels using high frequency welding techniques.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that both the forgoing general and the following detailed description are exemplary and explanatory only and are in no way tended to limit the scope of the invention.